Why does everybody hate Cait Sith?

[Squall of SeeD]

for a start Cait Sith would of turned the temple into the black materia even had we not approved coupled with the fact that he said that he kidnaped marlene and said that he would come along even if they didnt want him to...

I doubt he actually kidnapped her in the manner that he implied. I don't see Reeve as the type who would have kicked down the door of Elmyra's house with a swarm of gun-toting soldiers behind him to capture a little girl. He probably very simply just told Elmyra that she and Marlene would be safer in Kalm and offered them an escort to get there.

I didn't get the impression that Marlene was terrified when Cait Sith let her voice come through the radio he held in the Gold Saucer. She seemed more surprised than anything to be hearing their voices, especially Aerith's.

i do like him for the fact that he would do anything for his people... had (SPOILER)Reeve joined the party himself instead of haveing some big stuffed mog in your party the fact of the matter no matter how many times he could of died he would still have a replacement anyway, if (SPOILER)Reeve would have come out to the front line himself he would have earned my respect but he never did so i dont like him.

They never really went back toward Midgar until Disc 2, at which time (SPOILER)Reeve was going to go with them himself, but (SPOILER)the Shin-Ra soldiers had arrested him already and were still after him, so he had been taken in by some of Midgar's citizens:

(SPOILER)::Cait Sith comes back online::

Barret
"Well lookey-here. The Shinra manager's come back."

::Cait Sith stands up and goes over to the group and bows::

Cait Sith
"Uh, excuse me but..."
"I wanted to come with the main group, but I couldn't get
away......"
"So some people in Midgar took me in."

::He straightens back up::

Cait Sith
"I know I have a stuffed animal body, but I'll work really hard!"

So it's not really like he didn't want to. Besides, (SPOILER)being in Midgar allowed him to make sure everyone got in the Slums when Meteor started coming down, so it was probably best that he stayed there.

one thing i dont understand is when at the end of disk 2 he goes to midgar to check on his people when he should of already been there?

What scene are you referring to? They go to Midgar the first time because Diamond WEAPON was flying toward it and they were trying to protect it. They go back because Hojo went insane and was going to fire upon the Northern Crater with the Sister Ray a second time, putting Midgar in danger.